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The majority of the time they will fail closed. But it is possible for it to fail open, but it is rare. There are two kinds of thermostats. The really tiny ones usually stick closed. The longer, bigger ones are refered to as "fail-safe thermostats" because they are designed to stick open. The reasoning behind this is it is better to have no heat in your cabin than to have your engine overheat. However, this doesn't mean it's not getting "lazy;" opening too late, too slow, or not enough.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoTotally depends on the design & how it fails I'm afraid. Both are possibilities.
I'd say the only way to know is to run the engine for a bit and see if the top hose on the radiator gets hot when the 'stat should open. If it doesn't, and then engine temperature keeps going up, then the thermostat is probably stuck closed.
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Can a bad thermostat cause your car to run cold?
If stuck open the car will run cold. If stuck closed the car will run hot.
What happens when you put coolant into a Malibu without running the car?
When the car is cold the thermostat is closed. When the thermostat is closed the coolant does not circulate or get in to the engine block.
How do you determine if your thermostat is bad?
When the car is hot, squeeze the upper radiator hose. If it feels soft, then the thermostat is not opening and therefore bad. If you squeeze the hose and its hard to squeeze, then it is pressurized and the thermostat is open. That is one way to check if the thermostat is stuck closed. If the thermostat is stuck open, then in cold conditions the car will take a long time to produce hot air from the heater.
Why does a car thermostat fail?
They will get full of crud and start to stick.
Can a bad thermostat cause damage to your car?
Yes. If stuck closed the car will overheat. If stuck open the car will never warm up properly and the oil will slowly turn to sludge.
What does it mean when your car doesn't heat up sitting still?
The car's thermostat is bad and not working. Most likely the thermostat is stuck open. Thermostats are heat sensitive valves that open and close. If stuck in the open position the car never warms up. If stuck in the closed position it will over heat. http://auto.howstuffworks.com/cooling-system8.htm
Can a car overheat with a stuck open thermostat?
Usually the car would run cool, unless the thermostat is stuck partially open.
How do you know if your 95 geo prizm needs a thermostat change?
Thermostat can stick open or closed. If sticks open, car will take longer to warm up because coolant is constantly flowing thru engine. If thermostat is stuck closed, engine will eventually overheat. In order for all emission systems to work properly, thermostat needs to be working. For 1995 GEO Prizm, if thermostat is working correctly, car should maintain proper operating temperature after is warmed up. If any doubt about thermostat, changev it every few years as is inexpensive and easy to replace.
Car starts to overheat when idling and heater does not blow hot air radiator fan does not kick on when car heats up what could be the problem?
either the thermostat or the fan is no good. You would need to locate the thermostat and see if its stuck open or closed!
Breeze no heat and overheating what causes this?
No heat coming from the heater and the car overheating is usually the thermostat stuck closed. The thermostat is supposed to open up at a certain temperature allowing the engine to warm up quickly.
How do you know if your thermostat is stuck?
If the stat is stuck open,your car will slowly overheat and not reach normal operating temperature, if it is stuck closed it will overheat very quickly.
Can a stuck thermostat cause a temp gauge not to work?
yes if the thermostat is stuck open the gauge will read low the water or antifreeze will flow straight through the engine and radiater if it is stuck closed it will over heat your car
